Circuit voltage is not stated, but make sure the overload heaters are sized based on the motor-nameplate full-load current and not by lookup in Table 430-150. The table values are intended for branch-circuit and feeder sizing.
The term â€śmotorâ€¦service disconnect switchâ€ť is mentioned, and seems to be described as possibly applied â€śdownstreamâ€ť of the individual starters. You may want to instead use fused-disconnect switches applied â€śupstreamâ€ť as individual starter and motor disconnecting meansâ€”also sufficing as branch-circuit short-circuit and ground-fault protection.
The wiring proposed from a single 60-amp breaker to multiple starters sounds like it may be â€śdaisy-chained,â€ť for which the starter terminals are likely not intended in accommodating larger, possibly multiple conductors. A single disconnecting means for nine motors is not likely permitted in the case of building-ventilation motors.
Note also that local mechanical codes may additionally require individual motor-disconnecting means at each individual motor locationâ€”such as with non-fused disconnect switches.